1. Field of the Invention
This invention relates to ligand-receptor binding assay techniques. The determination of the presence or concentration of a ligand analyte which is a member of a specific binding paai ("sbp member") consisting of ligand and its complementary receptor, in serum or other body fluids relies increasingly upon specific binding assay techniques. These techniques are based upon formation of a complex between sbp members in which one or the other member of the complex may be labeled. In the case of a competitive specific binding assay technique, analyte in a sample of fluid being tested for its presence competes with a known quantity of labeled analyte in binding to a limited amount of a complementary sbp member. Thus, the amount of labeled analyte bound to the sbp member varies inversely with the amount of analyte in the sample. In immunometric assays, the analyte is usually a ligand and the assay employes a complementary sbp member and a second labeled receptor, usually an antibody. In such an assay, the amount of labeled receptor associated with the complex is directly related to the amount of analyte substance in the fluid sample.
The presence in the sample of an interfering substance that binds to a receptor being employed to bind with the analyte in question can be a serious factor in comprising the quantitative character of a ligand-receptor assay. The analyte is usually present in very small amounts. The interfering substance, which may be present in greater amounts, can bind to a significant number of receptor molecules and, thus, reduce assay sensitivity. In many situations, the amount of interfering substance will vary from sample to sample thereby preventing accurate reference to a standard or calibrator normally employed to provide for translating the observed signal into the concentration of the analyte. In order to enhance the accuracy of the assay, it is desirable to diminish or completely remove the contribution of the interfering substance to the observed signal.
2. Description of the Prior Art
U.S. Pat. No. 4,362,531 discloses agglutination immunoassays carried out with an agent to reduce non-specific interferences. An improved immunoassay sample determination process for determining the presence of a component of an antigen-antibody reaction in a sample, which process substantially eliminates non-specific interactions between the sample and the reaction vessel wall surfaces during the antigen-antibody reaction is disclosed in U.S. Pat. No. 4,414,324. U.S. Pat. No. 4,455,381 teaches an immunoassay method for proteins wherein the interference in the assay can be avoided by subjecting the fluid to protein-digestion, using for example an enzyme such as pepsin. A receptor steric hindrance immunoassay for receptor determination is disclosed in U.S. Pat. No. 4,130,462. U.S. Pat. No. 4,233,402 teaches reagents and method employing channeling.